The oxidation mechanisms of iron particles and NiCoCrAlY particles during plasma spraying process and its effect on the sprayed coatings were investigated by the in-flight particles collection setup and the gas shrouding. The results show that there are two oxidation mechanisms during in-flight oxidation: one is the diffusion oxidation; the other is the convective oxidation, which are decided by the distance from the spraying particles to the nozzle. The oxidation content increases with the increasing of the standoff distance. The shrouded gas can decrease the oxidation content of inflight particles and increase the oxidation resistance of NiCoCrAIY coatings.%利用粒子收集装置和附加氩气保护罩,研究了铁粒子和NiCoCrAlY粒子在等离子喷涂过程中的氧化行为及其对涂层性能的影响.结果表明,粒子在飞行过程中存在对流氧化和扩散氧化两种氧化机制,粒子的氧化方式取决于离开喷嘴的距离;离开喷嘴距离越长,粒子氧化越严重;采用附加氩气保护罩能明显减少喷涂过程中外界空气对粒子的氧化,降低涂层孔隙率,提高NiCoCrAlY涂层的抗高温氧化性能.
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